Superoxide Dismutase (SOD) Activity In Discolored Gingival Tissue Adjacent To Ni-Cr Porcelain Crowns

PFM technology is currently widely used in clinical, at the same time there have been some cause for concern, such as a few months after PFM restorations the adjacent gingival tissue swelling, shaded black, and even gingival atrophy, root exposure, what mentioned above seriously affect the effect of remediation. Recently Aesthetic dental restoration has received widespread attention. The cause of gingival discoloration for clinical research has become a hot spot, but the concrete mechanism has been in dispute. Some research indicated that after the Ni-Cr porcelain crowns restored, the gum color deterioration's patient proportion is more than other alloy porcelain crowns. Our experimental study is about the gum color deterioration after the Ni-Cr porcelain crowns restored.Objective:Collection of the clinical gathering discolored gingival tissue adjacent to PFMC and the normal gingival tissue, take the gingival tissue discoloration superoxide dismutase (SOD) activity for research. Discuss the injury mechanism of gingival discoloration.Materials and Methods:Experimental group: patients with metallic pigmentation after Ni-Cr porcelain crowns prosthesis, requesting reprosthesis, due to the aesthetic effect needing partial discolored gingival excision. a total of three cases. One cases were male, aged 29 years old, PFM restoration time for 27 months; two cases of women, aged 25 years old, 30-year-old, PFM restoration time is for 11 months, 21 months. Case inclusion criteria:①Once carried on the Ni-Cr porcelain crowns in 6 maxillary anterior;②prosthesis time more than six months;③aged 25-30 years old;④marginal fit;⑤good oral hygiene, exclusion of PFM restoration other teeth had no significant periodontal disease;⑥the gingival adjacent to the prosthesis is discoloration, and the curve is inharmonious.Control group: 2 patients(1 females and 1 male) with impacted tooth who need extraction without substantial health problems and pigmentations Take the clinical indicators - SBI, PD of the experimental group of patients.Lidocaine local infiltration anesthesia in the cut under the experimental group and control group gums, the specimens flushes away the bloodstain with normal saline syringe, after the gauze dips does, -4℃sealed frozen preservation, to be test.Using Xan-Xanthineoxidase system to determin the SOD activity of experimental group and control group, compares the color in wave length 546nm place, according to formula computation determination result.Results: Discussion:1. Experimental group's SBI, PD presents the inflammation change, after Ni-Cr porcelain crowns prosthesis, there is the existence of gingival inflammation.in our study, the experimental group's SOD vigor value compares the control group to be high, and presents downward trend with the time. The reason could be speculated as follows: PFM with a cytotoxic metal ion precipitation, lead to surrounding tissue inflammation, the release of inflammatory mediators, can make mitochondrial damage, activation of macrophagocyte, neutrophil aggregation, resulting to produce a large number of free radicals, and oxidation-antioxidant is imbalance in partial tissue, the scavenger of free radical—superoxide dismutase SOD activity decreased, Unable to clear the free radicals and the lipid peroxidation metabolites LPO, to accelerate the generation of melanin, LPO accumulation, melanocytes generated increased, inflammatory pigmentation appears. What because we carry on is the clinical experimental study, the run time is short, the selection sample size is small, still need to carry on the big sample long time observation, and take Series of studies to Clear the relationship between Ni-Cr materials and gingival discoloration...